I had a similar issue. First I formatted it for NTFS in Windows 7. Then I turning the DNR off, unplugging the drive, turning the DNR on, and replugged back in. I tried it 2 or 3 times, and eventually it saw it.
I also had the issue that after formatting it thru the tool, it would not start recoding to it. Again I tried rebooting, unplugging and replugging in... eventually, and mysteriously, it started working.